The present invention relates to an assembly device for an electronic component. The electronic component includes at least one semiconductor element which is contacted in a planar manner by a circuit substrate on each its lower side and its upper side. The present invention also relates to a method for assembling such an electronic component using such an assembly device.
Many power semiconductors have to be electrically contacted both on their structured upper side and their lower side. The electrical contacting of the lower side is generally accomplished by a so-called xe2x80x9cdie attachxe2x80x9d process. Here, the semiconductor is mounted by soldering or adhesive bonding to an electrically conductive support, such as a substrate, a cooling element or a pressed screen. The contacting of the upper side is usually done by a wire bonding process. In this connection, aluminum wires, for example, are fastened to the semiconductor element by ultrasound welding, continued to the electrically conductive support, and fastened there likewise by a wire bonding process.
For currents to be switched in power electronics, three to six bonding bridges have to be installed per semiconductor element. This is connected, on the one hand, with the considerable use of space for the bonding lands on the semiconductor element, and on the other hand, with a relatively high fault liability or failure rate. In addition, in the case of aluminum wire bonding, a single connection process is involved, which leads to considerable process times in the production of such electronic components, e.g., in the case of mass production. Finally, it should be mentioned that bonding bridges in power electronics cause leakage inductance that are not to be neglected.
In International Published Patent Application No. WO 98/15005 a sandwich construction method is described for electronic components which make do without the bonding bridges described above. For this purpose, the power semiconductor is contacted on its lower side and its upper side by a circuit substrate in a planar fashion.
The two circuit substrates should be oriented parallel to each other with the lowest possible tolerances for both the production of such an electronics component and its installation in equipment. The adjustment of the two circuit substrates required for this turns out to be a problem in practice.
The present invention relates to an assembly device for an electronic component in a sandwich type of construction, the use of which the two circuit substrates of the electronic component may be simply adjusted to each other.
The assembly device according to the present invention includes a first lower shell including an accommodation for the first of the two circuit substrates, an arrangement for the defined aligning of the first circuit substrate in the accommodation, and a second, upper shell including an arrangement for adjusting the second circuit substrate positioned on the semiconductor element.
The present invention also relates to a method for assembling such an electronic component using such an assembly device.
According to the present invention, the first circuit substrate is positioned in the accommodation of the first shell, and is aligned in a defined manner by using adjusting pins, which project from the side wall of the accommodation, and at least one correspondingly arranged and supported positioning pin in the x and the y direction, i.e., in the plane of the first circuit substrate. The semiconductor element is positioned on the first circuit substrate, and the second circuit substrate is positioned above the semiconductor element on top of the first shell. Then the first circuit substrate is aligned in a defined manner with the aid of adjusting pins, which project from the bottom wall of the accommodation, and at least two holding-down clamps in the z direction, i.e., perpendicular to the plane of the first circuit substrate. The second circuit substrate is adjusted in the x and the y direction in that adjusting pins arranged on the second shell are guided through indexing holes in the second circuit substrate and positioned in corresponding recesses in the first shell. The second circuit substrate is adjusted in the z direction in that the first Shell and the second shell are pressed against each other.
The assembly device according to the present invention may be used not only for mutual adjustment of the two circuit substrates to each other, but also as workpiece support during connecting processes, such as soldering or bonding.
The assembly device according to the present invention and the method according to the present invention may make possible not only a simple, and precise adjustment of the two circuit substrates of an electronic component constructed by sandwich type of construction, but also an individual development of the electronic component in regard to its dimensions and its outer shape. Thus, an electronic component constructed using the arrangement of the present invention may simply and in a secure process be molded or hermetically sealed, depending on the type of its final mounting location. It may also be possible to configure the electronic component, with respect to its dimensions, in accordance with SAT (surface mount technology) type, laid down in the international norm for standardized plastic packaging of electronic components, GATWICK-95. The back end production process is identical to the manufacturing of a standardized power housing. For further processing, then, the processes usually employed are available, such as surface mounting technique, or SAT. But beyond that, circuit substrates may be used whose geometry makes possible another kind of assembly of the electronic component. Thus, the assembly device according to the present invention is especially suitable for adjusting circuit substrates in the form of pressed screens. By inner and/or outer fusing of the connecting crosspieces of such pressed screens, the most varied geometries may be produced which, for example, permit assembly by using soldering, welding, riveting or by screws.
There are different possibilities for realizing the example embodiment of the assembly device and the implementation of the method according to the present invention. In this context, reference is made to the following description of an example embodiment of the present invention on the basis of the drawing.